Draft-producing device for locomotives



F'eh. H, mm.

E. PRAT DRAFT PRODUCING DEVICE FOR LOCOMOTIVES 2 sheets-sheet 1 Filed Apr. 2, 1920 Feb. 2m, 1923.. mwmm E. PRAT DRAFT PRODUCING DEVICE FOR LOCOMOTIVES Filed Apr. 2, 1920 2 sheets-sheet 2 nannies Feb. no, man.

nrarrn near, or rams, rrtnnonynssronon ro socrn'rn nus onmurnnns LOUIS ram:

n TIIRAGE mport, or rants, rte-anon.

DRAFT-PRODUCING DEVICE FOR LGCOMOTIVES.

Application filed Apri1 2, 1920. Serial No. 370,86l.

1 l (tZI iii/ mm it may concern Be it known that I, EMILE PHAT, citizen in the case of locomotives, the resistance to the flow of the gases through the nest of tubesis always considerable, and in modern engines, it is advisable to maintain in the smoke box an absolute pressure or about 200 to 300 millimeters water column beneath atmospheric pressure.

Forthe purpose of p-roducinga considerable fall of pressure below atmospheric pressure, the draft systems in common use, which are; dependent upon the expansion of steam, are of low efiiciency, the suction-tan system i being far more economical; but this latter system cannot be used on. locomotives unless it is provided with auxiliary steam devices which enable the draft to be maintained in case the locomotive, and therefore the tan stops, i

The object of the present invention is to fulfil these two conditions and to enable one method of operating to be easily changed to the other, ,while maintaining the highest possible eiiiciencyin the case or both. The apparatus for use in locomotives, comprising a fan through which are passed all the lur nace gases to be discharged,is characterized according to the present invention by the employment of amovablethrottling device which is capable, on the one hand, of torming, during normal working, an extension from the delivery nozzle of the fan. to the chimney, so as to continue the expansion of the furnace gases from the fan outlet, and, on the other hand, onbeing moved when the auxiliary steam jet is brought into operation, of insuring the expansion of the steam in stages so as to set up an induced draft for the furnace gases through the aspirator formed by the bi-conical portion of the chimney. in the form. generally recognized as the most advantageous, the delivery nozsic of the tan consists of a Venturi tube.

In the accompanying drawing, which shows, by way of example, one method of carrying out the invention, Fig. 1 is a section of the device on a locomotive smoke box under normal running conditions. Fig. 2 s a partial diagrammatic section or the throttling device in position for operating with auxiliary steam jot. Fig. 3 is a de tail view, showing a device for supporting and .operating the throttling device, this portlon having been omitted in Figs. 1 and 2 in order to sin'iplify the drawings. Fig. l an end view of the smoke box, showing the general arrangement of the fans. Fig. 5 is a diagrammatic representation of the form usuallyassumed by the stream of gases issuing from the nozzle of a fan.

Figure 6 is an enlarged diagrammatic sectional view showing the cooperative relation of the fan, its nozzle and adjacent parts in the same position as in Figure 1, the position of the parts shown in Figure 2 being indicated in dotted lines, and

Figure is an enlarged front elevation of the two steam inlets.

On the smoke box a of theflocomotive is arranged the intake of the tan b, which delivers through nozzle 0 into the bi-conical chimney d. This chimney is preferably horizontal, its rearward portion only being turned up. The movable throttling device 6 is adapted to be moved with reference to the nozzle 0, by any suitable means, for example by a threaded rod J, as shown in Fig.

3 (in order to simplify the drawing, only the end of this rod being shown in Fig. 1). Two annular auxiliary steam jets, f and h,

are also arranged round the nozzle 0.

In the ordinary course, the throttling device a takesup a position behind and in line with the nozzle (Fig; 1), its rearward edge bearingagainst the chimney (i so as to. shut it ofi completelyfrom the smoke box. Under these conditions, all the gases to be discharged pass through the fan, which delivers them through the nozzle 0 and the throttling device e, in which latter, the diiifusion begun in the nozzle is continued.

When the fan is stopped only the steam jet operates and the throttling device is moved into the position shown in Fig. 2..

with the contour is indicatedin Fig. adopting this shape of nozzle the loss of et- The steam is able to escape from the ring or from the ring it, according as it is exhaust steam comingtrom the pipe 9. or live steam coming from the pipe Moreover the two may operate at the same time.

On issuing from the ring'j' or it, the steam expands in the space comprised between the nozzle 0 and the throttling device 6. and aspirates a certain quantity of gas, the 1nix ture of gas and steam issuing from the other end oi the throttling device under s'u'liicient pressure for the further expansion of this mixture, in the chimney, to set up an inductive e'tlort under the influence of which the remainder of the gas is aspirated.

As the result oi these two successive expansions and ofthe conical (or more usually, bi-coni'cal) shape given to the throttling device a. the steam jet is utilized in a very satisfactory manner and the drat't produced is comparable to that furnished by the 'Vfan.

Thus with a single member such as the throttling device a. the working; of the locoj'niotiv'e can be maintained whether the tan be working or not.

The bi-c'onical 0r i' e'nturi-tubc form is adopted forthe nozzle 0 because experience has proved that, contrary to the idea previously held, the stream of gases issuing from the delivery nozzle-of a fan does not expandimmediately, but first of all contracts and then expands very nearly in accordance B'v ficiency due to eddies, is obviated and the discharge of the gases is facilitated.

For the sake of clearness only the employment o1 a single fan'has been referred to. but it follows, as a matter of course that.

'inorder to facilitate installation in locomotives. and for reasons of symmetry, as well as. in order to provide a reserve, it is desirable to provide several groups of: fans and chimneys. and more usually two, as shown in Fig.4.

It should also be noted that this system of draftproduction is capable of numeroi'is applications m the case of land or marine boilers. because (1) of the tendency to employ boilers with'a high rate of evaporation (2) powerful draft is necessary when in'lerlor fnelsare used-and (3) of the einployn'ient :ofheat regenerators which offer great resistance to the discharge of the smoke.

) VJhenitheannular'steam jet f is not in use, the exhaust steanidischarged from. the

engine cylinders by way of the pipe may be allowed to escape to the atmosphere through a branch pipe 222-; valves n and 0 interposed in the pipes f/ and m. resp ctively enabling the exhaust steam to be dircchul either to the ring 7' or into the atmosphere as may he required.

In my co-pending application Serial No. 370360 filed April .2. 19%). l have described an induced drai't device by ejector action in which a portion of gases pznsscs inside thc tan and the remaiinler outside the tan. means being provided to control the ratio oi the two portions. In my (xvi-pendingapplication Serial No. 370862 filed April i 920. I have Further described a draft device in which a tan divided into two parts simultaneously causes the draft of the combusflon gases to the chimney in one part oi thc tan and blows atmospheric air to the Furnace grate in the other part. But my prcsent application does not relate to any devicc oi" the kind. as it concerns a draft device in which the fan is always traversed. when working. by all of the gases. and in which when thc tan is out ot work. the gases are carricd along by the ejector action o t a stnun blast.

What I claim is:-

1. In a drait-producing device for loco-- motives. a chimney comprising; a convergent part and a divergent 1 art. a tan adaptcd to be traversed. when in operation. by the whole oi the furnace gases to be discharged a movable throttlin;, member adapted on the one hand to be moved into close contact with the divergent part oi the chimney. thus forming: an extension from the delivery nozzle of the v an for the expansion of the gases discharged from the latter. said member being adapted on the other hand to be removed from the chimney wall. means ior expanding steam in the space between the delivery nozzle oi the tan and the movable n'iember in the latter position. and means for further expanding.- the steam in the chimney at the outlet of said member.

2. in a draft-producing dcvicc to loco motives. a chimney comprising; a crmvcrgrent part and a divergent part. a Tan having: av discharge nozzle constituted as a Yenlnritube. a movable member adapted to form an extension oi said delivery nozzle when the tan is in operation. and to form an expansion passage tor steam when the tan is stopped.

In testimony uhcrcot l Hill;

llO 

